1. Field of the Invention
The invention is based on a device for supplying an internal combustion engine with fuel.
2. Description of the Prior Art
One such device is known from German Patent Disclosure DE 102 47 564 A1. In it, the fuel is delivered to the suction valve of a high-pressure pump with the aid of a fuel pump, metered as a function of demand via a metering unit; the fuel in the high-pressure pump is compressed to a pressure of up to 1600 bar and is fed via a high-pressure valve into a high-pressure reservoir, the so-called rail, to which the injection nozzles of an internal combustion engine are connected. They effect the actual injection of the fuel required for operation into the combustion chambers of the engine.
As a function of the rpm, an internal combustion engine requires variously large amounts of fuel. To have adequate amounts of fuel available in the rail under all operating conditions, the high-pressure pump is designed for the maximum possible demand of the associated engine. However, this has the disadvantage that in the partial-load range, unnecessarily large amounts of fuel are delivered to the rail and carried back into the fuel reservoir via an overpressure valve, which from an energy standpoint is not very satisfactory. To overcome this disadvantage, the fuel amount supplied to the high-pressure pump is metered as a function of the demand at the time, with the aid of the metering unit. The overpressure valve and the metering valve are separate, independent functional units. This increases the risk that overpressure will occur in the rail, and that mechanical damage from pressure can occur in the rail, the connecting lines, and/or the metering unit.